The present invention relates to a suspension for supporting a head slider provided with a write head element and a read head element, used in a magnetic disk drive (HDD) unit or in an optical disk drive unit for example, and to a head gimbal assembly (HGA) provided with the suspension.
In an HDD, magnetic write head elements for writing magnetic information onto magnetic hard disks and magnetic read head elements for reading magnetic information from the magnetic disks are in general formed on magnetic head sliders flying in operation above the rotating magnetic disks. The sliders are supported at top end sections of suspensions of HGAs, respectively.
In each suspension, one ends of two pairs of signal lines are electrically connected to a pair of terminal electrodes of the magnetic write head element and to a pair of terminal electrodes of the magnetic read head element formed on the magnetic head slider, respectively. These four signal lines run along the suspension and the other ends of these signal lines are electrically connected to external connection pads formed on the back end section or outside of the suspension, respectively.
Recently, a suspension using no lead wire for the signal lines or a lead line member, that is, a wireless suspension or a suspension using flexible print circuit (FPC) has widely spread.
The wireless suspension is configured by directly laminating a resin layer, a trace conductor layer and an overcoat layer on the suspension as for signal lines, or by fixing or laser-welding to the suspension a separated stainless steel thin plate on which a resin layer, a trace conductor layer and an overcoat layer are preliminarily formed.
The suspension with FPC is configured by adhering on a normal suspension a FPC fabricated by forming trace conductors on a resin base layer and by forming a resin overcoat layer on the resin base layer to cover the trace conductors.
At the top end section of the wireless suspension or the suspension with FPC, two write signal lines electrically connected to two terminal electrodes of the write head element and also two read signal lines electrically connected to two terminal electrodes of the read head element are in general formed as trace conductors running along opposite side edges of the suspension so as to reduce an influence from EMS noise. That is, the two write signal lines are formed as two trace conductors passing through one outrigger, and the two read signal lines are formed as two trace conductors passing through the other outrigger.
In the latest HDD, to satisfy the demand for further increase of record capacity, a track density becomes very high and thus a gap between the adjacent tracks of the magnetic disk becomes remarkably narrow. Therefore, a magnetic head used for writing onto and/or reading from such high track density magnetic disk is required to very precisely control its position along the track width direction.
In an HGA used in the high track density HDD, if the trace conductors are heated due to the write current, the thermal expansion of the suspension may occur to produce a displacement of a magnetic head slider attached on the suspension. Namely, in the conventional HGA, the pair of trace conductors for the write head element are formed on one outrigger of the suspension. Therefore, if only this one outrigger is heated by the write current of several tens mA, for example about 40-50 mA, and thermally expanded, the top end section of the suspension will be temporally deformed toward the lateral direction from its axis causing the displacement of the magnetic head slider toward the track width direction.
In case of the HGA used in the low track density HDD, such displacement of the slider due to the thermal expansion of the outrigger presents no problem. However, in case of an HGA used for the high track density HDD, such small displacement may become significant problems.
It is therefore an object of the present invention to provide a high track density adaptable suspension and an HGA with the suspension, whereby a displacement of a magnetic head due to thermal expansion of the suspension can be effectively prevented.
According to the present invention, a suspension for supporting a head slider which has at least one write head element with terminal electrodes and at least one read head element with terminal electrodes includes a resilient suspension member, and a lead conductor member including a pair of first trace conductors and a pair of second trace conductors. One ends of the pair of first trace conductors are electrically connected to the terminal electrodes of the at least one write head element, and one ends of the pair of second trace conductors are electrically connected to the terminal electrodes of the at least one read head element. At least part of the lead conductor member is fixed to the suspension member. The pair of first trace conductors are separately located at opposite side regions of the suspension member in a top end section of the suspension member, respectively.
According to the present invention, also, an HGA includes a head slider which has at least one write head element with terminal electrodes and at least one read head element with terminal electrodes, and the above-mentioned suspension for supporting at its top end section the head slider.
Since the pair of first trace conductors served to flow a write current there through are separately formed on opposite side regions of the suspension member in a top end section of the suspension member, respectively, heating sources of Joule heat are separated into the different side regions to reduce a local heating value itself. Also, since right and left side regions of the suspension member are heated with the same current, the amount of thermal expansion at these side regions becomes almost equal to each other resulting that both the side regions temporally deform the same direction along the axis of the suspension member. Therefore, no displacement of the head slider toward the track width direction occurs. As a result, a higher track-density-ready suspension and HGA can be obtained.
It is preferred that the top end section of the suspension member has two arms or outriggers running along opposite side edges of the suspension member and a head slider support or tongue coupled with top ends of the two arms, and that the pair of first trace conductors are formed on the two arms, respectively.
It is also preferred that the lead conductor member includes a resin layer directly laminated on the suspension member, the pairs of first and second trace conductors formed on the resin layer, and an overcoat layer for covering the pairs of first and second trace conductors.
It is preferred that the lead conductor member includes a resin layer laminated on a thin metal plate which is fixed to the suspension member, the pairs of first and second trace conductors formed on the resin layer, and an overcoat layer for covering the pairs of first and second trace conductors.
It is also preferred that the lead conductor member includes a FPC member consisting of a resin layer, the pairs of first and second trace conductors formed on the resin layer, and an overcoat layer for covering the pairs of first and second trace conductors.
It is also preferred that the pair of second trace conductors are separately located at opposite side regions of the suspension member in the top end section of the suspension member, respectively.
Preferred is also that the lead conductor member further includes ground (GND) conductors or source voltage (Vcc) conductors each inserted between the first trace conductor and the second trace conductor separately located at each side region. Each of the GND conductors or Vcc conductors serves as a shield pattern between the first trace conductor and second tarce conductor so that when harmonic components are produced on the first trace conductors due to overshoots at the rising and falling edges of the write current, no inductive electromotive force will be induced on the adjacent second trace conductors. Therefore, even if a write current with steep rising and falling edges is used in order to achieve a high data rate, change in performance and destruction of the read head element due to the produced inductive electromotive force can be effectively prevented. It should be noted that this advantage can be obtained only by additionally forming the GND conductor pattern or the Vcc conductor pattern during the conductor member forming process without increasing the number of the manufacturing processes and the manufacturing cost of the HGA.
It is preferred that the lead conductor member includes a resin layer directly laminated on the suspension member, the pairs of first and second trace conductors formed on the resin layer, the GND conductors or Vcc conductors formed on the resin layer, and an overcoat layer for covering the pairs of first and second trace conductors and the GND conductors or Vcc conductors.
It is also preferred that the lead conductor member includes a resin layer laminated on a thin metal plate which is fixed to the suspension member, the pairs of first and second trace conductors formed on the resin layer, the GND conductors or Vcc conductors formed on the resin layer, and an overcoat layer for covering the pairs of first and second trace conductors and the GND conductors or Vcc conductors.
It is preferred that the lead conductor member includes a FPC member consisting of a resin layer, the pairs of first and second trace conductors formed on the resin layer, the GND conductors or Vcc conductors formed on the resin layer, and an overcoat layer for covering the pairs of first and second trace conductors and the GND conductors or Vcc conductors.
It is further preferred that the suspension member includes a base plate, a load beam coupled with the base plate, and a resilient flexure fixed to a top end section of the load beam for mounting the head slider.
It is preferred that the at least one write head element and the at least one read head element are at least one magnetic write head element and at least one magnetic read head element, respectively. In this case, the at least one magnetic read head element may be a magnetoresistive effect (MR) read head element.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.